Cancer is an inherently genetic disease caused by the accumulation of germ-line and somatic mutations in genes controlling various cellular processes. Cancer cells maintain rapid proliferation by increasing energy generation (metabolism) and the rate of lipid, protein, and nucleotide biosynthesis. In fact, many of the frequently mutated tumor suppressor and oncogenes directly influence cellular metabolism, and specific mutations are observed in metabolic enzymes. For example, point mutations occur at high frequency in isocitrate dehydrogenase 1 and 2 (IDH1/2)-enzymes involved in central carbon metabolism-in low-grade gliomas and other tumor types. Patients with mutant IDH1 or IDH2 gliomas have significantly better prognoses, suggesting that mutant IDH creates metabolic deficiencies in these tumors. Understanding these metabolic deficiencies will allow for the development of optimal therapeutic strategies to treat tumors with such mutations. Prior research into the metabolic reprogramming induced by mutations in IDH1 has uncovered targets that selectively inhibit the growth of tumors with these mutations. The proposed research will apply similar rigorous systems-level techniques to advance our understanding of the metabolism of cells harboring heterozygous mutations in IDH2. Specifically, we will apply 13C and 2H tracing, mass spectrometry, and computation modeling to describe the flow of nutrients through the metabolic network in order to identify pathways critical to mutant IDH2 cells. Furthermore, we will carry out proof of concept studies to identify potential therapeutically usefu targets for treating mutant IDH2 cancers.